The Microsoft flaws were fixed likely within months of the hack.
Microsoft Corp's secret internal database for tracking bugs in its own software was broken into by a highly sophisticated hacking group more than four years ago, according to five former employees, in only the second known breach of such a corporate database.
The company did not disclose the extent of the attack to the public or its customers after its discovery in 2013, but the five former employees described it to Reuters in separate interviews. Microsoft declined to discuss the incident.
